Bonding Apparatus, Bonding Method and Article Manufacturing Method

The present disclosure relates to a bonding apparatus, a bonding method and an article manufacturing method.

Japanese Patent Laid-Open No. 2022-169798 proposes a technique of, when bonding a die (such as a chip or a semiconductor chip) as a bonding object to a substrate (bonding target object), bonding the die to the substrate with the die bent into a downward convex shape.

In the conventional technique, by bonding the die to the substrate with the die bent, bonding reliability can be improved. However, by bending the die, when it is bonded to a flat substrate, a shape error occurs in the die, and bonding accuracy between the die and the substrate decreases.

The present disclosure provides a technique advantageous in bonding reliability and bonding accuracy.

According to one aspect of the present disclosure, there is provided a bonding apparatus that performs a bonding operation of bonding a bonding object to a bonding target object, including a driving unit configured to perform driving such that the bonding object is bonded to the bonding target object, and a control unit configured to control the bonding operation such that a bonded shape of the bonding object after the bonding object is bonded to the bonding target object achieves a predetermined distortion shape.

Further aspects of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings.

Hereinafter, embodiments will be described in detail with reference to the attached drawings. Note, the following embodiments are not intended to limit the scope of the claimed disclosure. Multiple features are described in the embodiments, but limitation is not made to an disclosure that requires all such features, and multiple such features may be combined as appropriate. Furthermore, in the attached drawings, the same reference numerals are given to the same or similar configurations, and redundant description thereof is omitted.

A description will be given below assuming that a bonding object is a separated die including a semiconductor element, and a bonding target object is a die including a semiconductor element formed on a substrate (wafer), but the bonding object and the bonding target object are not limited thereto.

The bonding target object includes, in addition to the die including the semiconductor element formed on the substrate, for example, a silicon interposer as a silicon wafer with wiring formed thereon, and a glass interposer as a glass wafer with wiring formed thereon. The bonding target object also includes an organic interposer as an organic panel (PCB) with wiring formed thereon, a wafer formed with a semiconductor element, to which some dies including semiconductor devices have already been bonded, and the like.

The bonding object includes, in addition to the separated die, for example, a stack of some already separated dies, a small piece of a material, an optical element, a MEMS, a structure, or the like. The bonding method of the bonding object and the bonding target object is also not limited. The bonding method of the bonding object and the bonding target object includes, for example, bonding using an adhesive agent, temporary bonding using a temporary adhesive agent, bonding by hybrid bonding, atomic diffusion bonding, vacuum bonding, bump bonding, and the like. In this manner, the bonding method of the bonding object and the bonding target object includes various temporary bonding methods and permanent bonding methods. A bonding step includes various processes required for each bonding method, for example, cleaning, applying an adhesive agent, activating the surface, applying pressure, heating, or the like.

Industrial application examples of the bonding apparatus as one aspect of the present disclosure are, for example, application examples described below.

The first application example is manufacturing of a stacked memory. When the bonding apparatus as one aspect of the present disclosure is applied to manufacturing of a stacked memory, the bonding object is a separated memory die, and the bonding target object is a memory die as a semiconductor element formed on a wafer. In manufacturing of a stacked memory, in general, about eight layers are stacked. Hence, in bonding of the eighth layer, the bonding target object is a substrate as the wafer to which six layers of memory dies have already been bonded. Note that the final layer may be a driver die for driving the memories.

The second application example is heterogeneous integration of a processor. The mainstream of a conventional processor is an SoC obtained by forming a logic circuit and an SRAM in one semiconductor element. To the contrary, in heterogeneous integration, respective elements are manufactured on separate wafers while applying a process optimal for each element, and bonded to manufacture a processor. This can implement cost reduction and yield improvement of the processor. When the bonding apparatus as one aspect of the present disclosure is applied to heterogeneous integration, the bonding object is a die such as an SRAM, an antenna, or a driver separated after probing. The bonding target object is a logic die as a semiconductor element formed on the wafer. Normally, different dies are sequentially bonded. Hence, the bonding objects on the bonding target object sequentially increase. For example, in a case of starting bonding from an SRAM, when bonding the die next to the SRAM, the logic wafer with the SRAM bonded thereto serves as the bonding target object.

The third application example is 2.5D bonding using a silicon interposer. The silicon interposer is a silicon wafer with wiring formed thereon. The 2.5D bonding is a method of bonding separated dies using the silicon interposer, thereby electrically bonding the dies. When the bonding apparatus as one aspect of the present disclosure is applied to die bonding to the silicon interposer, the bonding object is a separated die, and the bonding target object is a silicon interposer as a silicon wafer with wiring formed thereon. In general, a plurality of types of dies are bonded to the silicon interposer. Hence, the bonding target object also includes a silicon interposer with several dies bonded thereto.

The fourth application example is 2.1D bonding using an organic interposer or a glass interposer. The organic interposer is an organic panel (PCB substrate or CCL substrate) used as a package substrate, on which wiring is formed. The glass interposer is a glass panel with wiring formed thereon. The 2.1D bonding is a method of bonding separated dies to the organic interposer or the glass interposer, thereby electrically bonding the dies by the wiring on the interposer. When the bonding apparatus as one aspect of the present disclosure is applied to die bonding to the organic interposer, the bonding object is a separated die, and the bonding target object is an organic panel with wiring formed thereon. When the bonding apparatus as one aspect of the present disclosure is applied to die bonding to the glass interposer, the bonding object is a separated die, and the bonding target object is a glass panel with wiring formed thereon. In general, a plurality of types of dies are bonded to the organic interposer or the glass interposer. Hence, the bonding target object also includes an organic interposer or a glass interposer with several dies bonded thereto. The fifth application example is heterogeneous substrate bonding. For example, in the field of infrared image sensors, InGaAs is known as a high sensitivity material. Accordingly, if InGaAs is used for a sensor unit that receives light, and silicon capable of implementing high-speed processing is used for a logic circuit that extracts data, a high-sensitivity high-speed infrared image sensor can be manufactured. However, from InGaAs crystal, only substrates (wafers) whose diameter is as small as 4 inches are mass-produced, which is smaller than a mainstream silicon wafer having a size of 300 mm. Hence, a technique of bonding a separated InGaAs substrate to a 300-mm silicon wafer with a logic circuit formed thereon has been proposed. The bonding apparatus as one aspect of the present disclosure can also be applied to heterogeneous substrate bonding for bonding substrates made of different materials and having different sizes. When the bonding apparatus as one aspect of the present disclosure is applied to heterogeneous substrate bonding, the bonding object is a small piece of a material such as InGaAs, and the bonding target object is a substrate such as a silicon wafer with a large diameter. Note that the small piece of the material is a slice of a crystal. The piece is preferably cut into a rectangular shape.

is a view schematically showing the arrangement of a bonding apparatus BD as one aspect of the present disclosure. The bonding apparatus BD performs a bonding operation of bonding a separated die(bonding object) to an arbitrary position (bonding target portion) on a wafer(bonding target object) serving as a substrate. The dieis provided while being arrayed (held) on a dicing tape put on a dicing frame. In this specification, as shown in respective drawings, directions are indicated on an XYZ coordinate system. Typically, an XY plane is a plane parallel to the horizontal plane, and a Z-axis is an axis parallel to the vertical direction. X-, Y-, and Z-axes are examples of directions that are orthogonal to each other or cross each other.

As shown in, the bonding apparatus BD includes a pickup unitand a bonding unit, which are arranged on a basedamped by a mount. In this embodiment, the pickup unitand the bonding unitare arranged on one base. However, the pickup unitand the bonding unitmay individually be arranged on separate bases.

The bonding apparatus BD further includes a control unit CNT that controls respective units of the bonding apparatus BD. The control unit CNT is formed by, for example, a PLD (an abbreviation of Programmable Logic Device) such as an FPGA (an abbreviation of Field Programmable Gate Array), an ASIC (an abbreviation of Application Specific Integrated Circuit), a general-purpose or dedicated computer (information processing apparatus) installed with a program, or a combination of all or some of them. The control unit CNT operates the bonding apparatus BD by comprehensively controlling the respective units of the bonding apparatus BD, for example, the pickup unitand the bonding unitin accordance with a program stored in a storage unit.

The pickup unitincludes a pickup headand a release head. The pickup unitpeels the dieto be bonded to the waferfrom the dicing tape by the release head, and holds the diepeeled from the dicing tape by sucking it with the pickup head. The pickup headrotates the dieby, for example, 180° and passes it to a bonding headof the bonding unit.

The pickup headcontacts the bonding surface of the die. Hence, in an application to a bonding method of performing bonding by activating the surface, like hybrid bonding, it is preferable to process the surface of the pickup headthat comes into contact with the bonding surface. For example, it is preferable to process the surface as a highly stable surface with a diamond like carbon (DLC) coating or a fluorine coating, or reduce the contact area by processing the surface into a small shape such as a pin shape with a high density. Alternatively, a noncontact holding method like a Bernoulli chuck or a method of preventing contact with the bonding surface by holding a side surface or an edge portion of the diemay be used.

The bonding unitfunctions as a bonding device configured to perform a bonding operation of bonding the dieto the wafer. The bonding unitincludes a stage baseand an upper base. A wafer stageis mounted on the stage base. The wafer stageis driven concerning the X direction and the Y direction by a driving mechanismsuch as a linear motor. The driving mechanismmay further be configured to drive the wafer stageconcerning a rotation about an axis parallel to the Z direction. Instead of the driving mechanismdriving the wafer stageconcerning the rotation about the axis parallel to the Z direction, the bonding headmay drive the dieconcerning the rotation about the axis parallel to the Z direction. The driving mechanismfunctions as a positioning mechanism that changes the relative position between a wafer chuck(or the wafer) and the bonding head(or the die).

A die observation camerais provided on the wafer stage. The die observation cameraobtains an image by capturing the dieheld by the bonding head. From the image obtained by the die observation camera, the control unit CNT detects (specifies) the position of the feature portion of the dieheld by the bonding head. A bar mirroris provided on the wafer stage. The bar mirroris used as the target of an interferometer.

In this embodiment, the bonding headfunctions as the first holding unit that holds the die. The wafer stagefunctions as the second holding unit that holds the wafervia the wafer chuck.

In this embodiment, the wafer stagefunctions as a support structure that supports the wafer chuckand the die observation camera. The wafer stageserving as the support structure includes the first end face (the left end face in) on the side where the dieis conveyed to the bonding head, and the second end face (the right end face in) on the opposite side of the first end face. The die observation camerais arranged between the first end face and a virtual plane that passes through the center of the wafer stage(support structure) and is parallel to the first end face. In another viewpoint, the die observation camerais arranged between a predetermined position in the path to convey the dieto the bonding headand the wafer chuck. This configuration is advantageous in decreasing the driving amount of the wafer stagerequired to observe the dieheld by the bonding headby the die observation cameraand thus improving throughput.

A wafer observation camerais provided on the upper base. The wafer observation cameraobtains an image by capturing the waferheld by the wafer chuck(wafer stage). From the image obtained by the wafer observation camera, the control unit CNT detects (specifies) the position of the feature portion of the waferheld by the wafer chuck. Based on the position of the feature portion of the wafer, the control unit CNT also obtains the positions of a plurality of bonding target portions on the wafer.

The upper baseis further provided with the interferometerfor measuring the position of the wafer stageusing the bar mirror, and the bonding headfor holding the diepassed from the pickup headand bonding it to the bonding target portion on the wafer.

In this embodiment, the upper basefunctions as a support structure that supports the bonding headand the wafer observation camera. The upper baseserving as the support structure includes the third end face (the left end face in) on the side where the dieis conveyed to the bonding head, and the fourth end face (the right end face in) on the opposite side of the third end face. The wafer observation camerais arranged between the third end face and a virtual plane that passes through the center of the upper base(support structure) and is parallel to the third end face. This configuration is advantageous in decreasing the driving amount of the wafer stagerequired to observe the waferheld by the wafer chuckby the wafer observation cameraand thus improving throughput.

The bonding headis driven concerning the Z direction by a driving mechanismsuch as a linear motor. The driving mechanismmay further be configured to drive the bonding headconcerning the X direction and the Y direction, or may be configured to drive the bonding headconcerning the rotation about the axis parallel to the Z direction.

When bonding the dieto the bonding target portion on the wafer, for example, the driving mechanismdrives the bonding headdownward (−Z direction), thereby bonding the dieheld by the bonding headto the bonding target portion on the wafer. Alternatively, the driving mechanismmay drive the wafer stageupward (+Z direction), thereby bonding the dieto the bonding target portion on the waferheld by the wafer stage(wafer chuck). Note that a driving mechanism (not shown) may drive the wafer chuckupward, thereby bonding the dieto the bonding target portion on the waferheld by the wafer chuck. In this manner, the driving mechanismsandfunction as a driving unit that drives at least one of the bonding head(the dieheld by the bonding head) and the wafer stage(the waferheld by the wafer stage) to bond the dieto the wafer.

In this embodiment, the configuration is employed in which the pickup headrotates the dieby 180° and passes it to the bonding head. However, by providing one or more die holding units between the pickup headand the bonding head, the pickup headmay pass the dieto the die holding unit, and the die holding unit may pass the dieto the bonding head. Alternatively, a driving mechanism that drives the bonding headmay be provided and drive the bonding headsuch that the bonding headreceives the diefrom the pickup head. Note that, in order to improve productivity, the bonding apparatus BD may include a plurality of pickup heads, a plurality of release heads, and a plurality of bonding heads.

In this embodiment, when bonding the dieto the wafer, in order to improve bonding reliability, the bonding headbonds the dieto the waferwith the diebent into a convex shape toward the waferside, that is, bending the dieinto a downward convex shape. More specifically, as shown in, the dieis bent into a shape with the protruding central portion, and brought into contact with the wafer. Thus, the dieis gradually bonded to the waferwhile pushing air from the central portion toward the peripheral portion. However, when bonding the dieto the waferwith the diebent, as shown in, the shape of the dieis distorted, and a shape error (to be referred to as a “bonding distortion” hereinafter) occurs in the die. The bonding distortion occurring when bonding the dieto the waferwith the diebent causes a deviation in the bonding position of the diewith respect to the wafer, resulting in a decrease in bonding accuracy between the dieand the wafer.

The bonding distortion occurring when bonding the dieto the waferis caused by die information concerning the die, a bonding control condition concerning the bonding operation of bonding the dieto the wafer, or the like. The die information includes, for example, the thickness of the die, the size of the die, the material of the die, the stress of the semiconductor element formed on the die, and the like. The bonding control condition includes, for example, the bending amount and bending shape of the die(the central portion relative to the peripheral portion), the relative velocity between the dieand the waferwhen bonding the dieto the wafer, and the like. The bonding control condition also includes the friction coefficient of the bonding headholding the die, the holding force of the bonding headholding the die, and the like.

Therefore, in this embodiment, the bonding distortion is controlled by adjusting, in accordance with the die information, the bonding control condition concerning the bonding operation of bonding the dieto the wafer. For example, the control unit CNT controls the bonding operation of bonding the dieto the wafersuch that the bonded shape of the dieafter the dieis bonded to the waferachieves a predetermined distortion shape.

With reference to, the bonding operation (bonding method) in the bonding apparatus BD will be described. As described above, in this embodiment, the bonding operation includes an operation of bonding the dieto the waferwith the diebent into a downward convex shape (a convex shape toward the waferside). This bonding operation is performed by the control unit CNT comprehensively controlling the respective units of the bonding apparatus BD as described above. Note that a preparation step of preparing the dieand the waferand a loading step of loading the prepared dieand waferto the bonding apparatus BD have been performed.

In step S, the control unit CNT obtains die information concerning the die, and a target amount of the bonding distortion of the die. As described above, die information includes at least one of the thickness of the die, the size of the die, the material of the die, and the stress of the semiconductor element formed on the die. A target amount of the bonding distortion of the dieincludes the target shape of the bonded shape of the dieafter the dieis bonded to the wafer, that is, a predetermined distortion shape to be intentionally generated in the die. In this manner, in this embodiment, the control unit CNT also functions as an obtainment unit that obtains die information and a target amount of the bonding distortion (predetermined distortion shape). Note that the control unit CNT may further obtain, in addition to die information and a target amount of the bonding distortion, wafer information concerning the waferand bonding environment (temperature, humidity, air pressure, apparatus status, or the like).

The target amount of the bonding distortion may be specified by, for example, the distortion amount of each component such as a magnification component, a third-order component, or a higher-order component, or may be specified by the distortion amount at the bonding target portion on the wafer.

For example, the control unit CNT obtains die information and the target amount of the bonding distortion input by the user via an input unit (user interface) of the bonding apparatus BD. However, as die information, the control unit CNT may obtain, from a die measurement unit of the bonding apparatus BD, the thickness of the dieand the size of the diemeasured by the die measurement unit. Similarly, as a target amount of the bonding distortion, the control unit CNT may obtain, from a wafer measurement unit of the bonding apparatus BD, the shape of the bonding target portion (the distortion amount of the bonding target part) on the wafermeasured by the wafer measurement unit.

In step S, based on the die information and the target amount of the bonding distortion obtained in step S, the control unit CNT calculates a bonding control condition concerning the bonding operation of bonding the dieto the wafer. As described above, a bonding control condition includes at least one of the bending amount and bending shape of the die, the relative velocity between the dieand the wafer, the friction coefficient of the bonding head, and the holding force of the bonding head.

From the die information, the control unit CNT calculates a bonding control condition for the bonded shape of the dieafter the dieis bonded to the wafer, that is, the bonding distortion occurring in the dieto achieve the target amount (for the bonded shape to achieve a predetermined distortion shape) (functions as a calculation unit). The control unit CNT calculates a bonding control condition for bringing the bonding distortion close to the target amount within constraints that can be realized by the bonding apparatus BD, for example, using an optimization method such as linear programming or a machine learning method. Note that the bonding control condition for bringing the bonding distortion close to the target amount means a bonding control condition for bringing the bonding distortion within a predetermined allowable error (margin) range with respect to the target amount of the bonding distortion.

Alternatively, as shown in, the control unit CNT may calculate a bonding control condition for the bonding distortion occurring in the dieto achieve the target amount by using the sensitivity representing the relationship among die information, a bonding control condition, and a bonding distortion (amount thereof) occurring in the die.shows the sensitivity representing the relationship among the thickness of the dieas the die information, the bending amount of the dieas the bonding control condition, and the magnification component of the bonding distortion (amount thereof) occurring in the die. With reference to the sensitivity shown in, the control unit CNT calculates, as the bonding control condition, the bending amount of the diecorresponding to the target amount of the magnification component of the bonding distortion from the thickness of the dieobtained as the die information.

In step S, the control unit CNT causes the wafer stage(wafer chuck) to hold the waferloaded in the bonding apparatus BD. A step of holding the waferby the wafer stageincludes a bonding preparation step for bonding the dieto the wafer. The bonding preparation step includes, for example, a step of measuring and positioning an alignment mark formed in the wafer, a step of measuring and levelling the surface position of the wafer, and the like.

In step S, the control unit CNT causes the bonding headto hold the dieloaded in the bonding apparatus BD. A step of holding the dieby the bonding headincludes a bonding preparation step for bonding the dieto the wafer. The bonding preparation step includes, for example, a step of measuring and positioning an alignment mark formed in the die, a step of measuring and leveling the surface position of the die, and the like.

In step S, the control unit CNT bonds the dieheld by the bonding headin step Sto the wafer(bonding target portion thereof) held by the wafer stagein step Sin accordance with the bonding control condition calculated in step S(bonding step). In other words, the control unit CNT controls the bonding operation of bonding the dieto the wafersuch that the bonded shape of the dieafter the dieis bonded to the waferachieves the predetermined distortion shape.

In step S, the control unit CNT determines whether all of the diesto be bonded to the waferhave been bonded to the wafer(bonding target portions thereof). In general, about 100 diesare bonded to one wafer. If not all of the dieshave been bonded to the wafer, the process returns to step S, and steps Sand Sare repeated until all of the diesare bonded to the wafer. On the other hand, if all of the dieshave been bonded to the wafer, the process transitions to step S.

In step S, the control unit CNT unloads the waferwith all of the diesbonded thereto from the wafer stage(wafer chuck).

In step S, the control unit CNT determines whether the dieshave been bonded to all of the wafersto undergo a lot process. If the dieshave not been bonded to all of the wafers, the process returns to step S, and steps S, S, and Sare repeated until the diesare bonded to all of the wafers. On the other hand, if the dieshave been bonded to all of the wafers, the bonding operation is terminated. Note that, in general, 25 wafersare processed as one lot, but there is also a case in which a plurality of lots are consecutively processed. In this case, the bonding operation of bonding the dieto the waferis repeated in accordance with the same bonding control condition until the waferor the die(the type thereof) is changed.

As described above, according to this embodiment, when bonding the dieto the waferwhile bending the dieinto a downward convex shape, it is possible to control the bonding operation such that the bonded shape of the dieafter the dieis bonded to the waferachieves a predetermined distortion shape. Hence, in this embodiment, it is possible to suppress a deviation in the bonding position of the diewith respect to the waferwhile improving bonding reliability between the dieand the wafer. This is advantageous in bonding accuracy between the dieand the wafer.

In this embodiment, an example of bending the dieas the bonding object has been described. However, the waferas the bonding target object may be bent, or both the dieand the wafermay be bent.

Here, with reference to, the specific configuration of the bonding headfor bending the dieinto a downward convex shape will be described. As shown in, in the bonding head, a cavity portion CA (cavity) is formed on the back side of a holding surface HS (chuck) for holding the die, and a pressure adjustment mechanism (not shown) is connected to the cavity portion CA. By adjusting the pressure in the cavity portion CA via the pressure adjustment mechanism, it is possible to bend the dieheld on the holding surface SH. More specifically, by increasing the pressure in the cavity portion CA, it is possible to bend the dieinto a shape (downward convex shape) with the central portion protruding downward (the waferside) from the peripheral portion. By decreasing the pressure in the cavity portion CA, it is possible to bend the dieinto a shape (upward convex shape) with the central portion protruding upward (the opposite side of the wafer) from the peripheral portion. Note that the shape of the holding surface SH (chuck) may be deformed in advance, and the bending shape of the diemay be adjusted by the pressure in the cavity portion CA. By adjusting the thickness between the holding surface SH and the cavity portion CA, it is also possible to change the bending shape of the dieto an R shape, a quadratic shape, or other shape. Hence, it is preferable that the configuration of the bonding headis selectable (interchangeable) in accordance with the shape of the dieor the target bending shape of the die.

show another example of the specific configuration of the bonding headfor bending the dieinto a downward convex shape. Referring to, the bonding headincludes a plurality of vacuum suction portionsfor chucking the die. As shown in, the plurality of vacuum suction portionsfunction as a plurality of holding mechanisms that respectively hold a plurality of different portions of a surfaceof the dieon the opposite side of a bonding surface(the surface on the waferside). As shown in, by driving each of the plurality of vacuum suction portionsin the horizontal direction (the first direction parallel to the bonding surfaceof the die) and the vertical direction (the second direction crossing the first direction), it is possible to bend the dieinto a downward convex shape. Particularly, in the bonding headshown in, by driving the vacuum suction portionsin the horizontal direction to distort the die, the distortion shape of the dieupon bonding the dieto the wafercan be reduced. In this embodiment, a case of holding the dieby vacuum suction in the bonding headhas been described. However, the diemay be held by an electrostatic force. It is also possible to adjust the bending shape and bending amount of the dieby individually controlling the driving directions and driving amounts of the plurality of vacuum suction portions. In this embodiment, the bonding headis constituted by three vacuum suction portionsas shown in. However, in practice, by constituting the bonding headby a large number of vacuum suction portionsarranged in an array, it is possible to precisely bend the die.